The proper height of the bicycle seat for the cyclist is crucial for protecting the cyclist from being injured during operation the bicycle and also for obtaining maximum efficiency of the operation of the bicycle. The adjustable bicycle seat is a trend for most of the bicycles when considering the cost of custom-made bicycle frames.
The existed bicycle seat adjustable devices use an adjustable mechanism located between the seat post and the seat tube so as to control the linear movement between the seat post and the seat tube. The conventional seat adjustable devices generally include mechanical adjustable devices, hydraulic/pneumatic adjustable devices, and hybrid adjustable devices which uses air and hydraulic media to adjust the seat. The mechanical adjustable devices use mechanical parts to set the relative height between the seat and the seat tube. The hydraulic/pneumatic adjustable devices use hydraulic media such as oil or air to achieve the purposes of adjustment of the seat. The hybrid adjustable devices utilize both of the air and hydraulic oil to adjust the height of the seat relative to the seat tube.
Each of the mechanical adjustable devices, hydraulic/pneumatic adjustable devices, and hybrid adjustable devices has a control unit so as to activate the adjustable device to allow the seat to be movable relative to the seat tube, when the seat is adjusted to a desired height, the control unit is locked to set the height of the seat. The control unit can be connected to the seat tube or the seat post directly so as to control the adjustable device. Alternatively, the control unit can be connected to any position of the bicycle frame other than the seat post and the seat tube.
One of the seat adjustable devices is disclosed in U.S. Pat. No. 7,083,180 and comprises a control unit located in the seat tube and the user can pivot a lever to push the rod in the adjustable device to seal or open the oil paths in the seat post and the seat tube so as to adjust the position of the seat.
Another adjustable device is disclosed in Taiwan Utility Patent Application No. 097223637 and comprises an inner tube which has an axial adjustment slot with two inclined insides, multiple holes are located at the bottom of the slot. An outer tube is mounted to the inner tube which is movable linearly relative to the outer tube. A cap seals the bottom of the outer tube and has a position rod extending into the outer tube. A spring is located in the outer tube and has one end extending through the positioning rod and the other end of the spring contacts the inner tube. An action unit extends through the outer tube and the slot, and includes a positioning member which is engaged with one of the holes. The positioning member has inclined surfaces which are matched with the inclined insides of the slot so that the positioning member is movable in the radial direction to control the relative position between the inner and outer tubes.
Yet another adjustable device is disclosed in Taiwan Utility Patent Application No. 094204651 and comprises a rise device and a control device, wherein the rise device has a spring and a locking member located in the recess of the seat tube. The locking member has a block and a passage, multiple hard sleeves, soft sleeves, washers and a base connected to the seat post. The base has protrusions on the periphery thereof to form a connection space. A washer, a locking member and a rod are located in the connection space. The control device has a lever and a cable which is fixed to a board by the locking member. The connection space of the seat tube has a closed end and the cable extends through the seat post. A flange extends from a mediate portion of the seat post and multiple blocks are connected to the lower end of the seat post to form connection slots.
The first two prior adjustable devices provide the switch close to the seat tube or the seat post, wherein the switch of the first adjustable device is directly connected to the rod so as to control the linear movement of the seat post and is suitable cooperated with the hydraulic/pneumatic adjustable devices. The second adjustable device provides an engaging device located between the seat post and the seat tube and has multiple holes located axially such that the positioning member is engaged with one of the holes to seat the height. The third adjustable device provides the lever outside of the seat post and the seat tube, and the user can operate the lever. The rise device is connected with a cable which activates the action of adjustment.
However, the hydraulic/pneumatic adjustment devices are restricted by the position of the rod so that the rod has to be connected to the related hydraulic/pneumatic parts. The rod extends downward from the post tube to the valve unit so that the most of the parts are located on the top section of the seat tube and the action unit is located close to the clamp unit. If the rod extends upward from the seat tube and is connected to the valve unit, the action unit has to be located at the lower portion so as to be connected to the rod and control the movement of the rod.